This invention relates to a lever switch device in which a switch can be activated by pressing an operation lever in the longitudinal direction, or tilting the operation lever, and particularly to a multi-direction switch device that may be utilized as a so-called joystick or the like having a lever tiltable in multiple directions. The invention also relates to methods for activating and connecting switches.
A lever switch device is disclosed in Japanese Utility Model Publication (Kokai) No. SHO-61-201244. As shown in FIG. 1, the lever switch device comprises an operation lever 72. The operation lever 72 includes a substantially hemispherical rotor 73 that slidingly contacts a hemispherical guide face 71 of an upper hollow portion of a housing 70 so as to be rotatably guided. The rotor 73 also includes a sliding rod 74 that is slidably fitted into the rotor 73 so as to pass through the center of the rotor 73.
When a knob 75 at the upper end of the sliding rod 74 is pressed under the neutral state of the operation lever 72, an operation pin 76 is pressed down by the lower end of the sliding rod 74, whereby a switch 77 disposed under the operation pin 76 is activated. When the knob 75 is released, the operation lever 72 returns to the original state by a return spring 80.
When the operation lever 72 is tilted from the neutral state, the sliding rod 74 and the rotor 73 are rotated as an integral unit so that an operation pin 78 is pressed down by the outer edge of the lower face of the rotor 73, whereby a switch 79 disposed under the operation pin 78 is activated. When the operation lever 72 is released, the operation lever 72 is returned to the original state by a return spring 81.
In the structure of the prior art lever switch device, the sliding rod 74 and the rotor 73 can be rotated under the state where the knob 75 is pressed down by a pressing operation of the operation lever 72, and the knob 75 can be pressed down under the state where the sliding rod 74 and the rotor 73 are rotated integrally by a tilting operation of the operation lever 72. In other words, this conventional structure is not provided with means for preventing the operation lever 72 from being concurrently subjected to both the pressing and tilting operations.
Consequently, there may arise a case where the switch 77, which can be activated by a pressing operation, and the switch 79, which can be activated by a tilting operation, are simultaneously activated. As a result, circuits that operate in accordance with the activation state of the switches 77 and 79 may erroneously operate.
Further, in the conventional lever switch device, for guiding and supporting the operation lever 72 in a tiltable manner, the hemispherical outer face of the rotor unit 73 that supports the operation lever 72 passing therethrough, and the hemispherical guide face 71 of the housing 70 slidingly contact each other, so that the operation lever 72 is tilted about the center of the hemispherical face.
In such a device in which guiding and supporting are realized by causing hemispherical faces to slidingly contact each other over a wide area, foreign substances such as dust enter into the space between the hemispherical guide face 71 of the housing 70 and the hemispherical outer face of the rotor unit 73. The foreign substances cannot be easily discharged and remain trapped between the faces. When such a phenomenon happens, the load of operating the operation lever 72 is increased, and there may arise a problem in that, even when the operating force is removed, the operation lever fails to return to the neutral position.
A switch device of such a type is used in, for example, a controller of a car navigation system. For example, the device is used in such a manner that, a display state is changed by tilting a lever to the right side to scroll a map displayed on a monitor screen in the right direction, and by tilting the lever to the upper side to scroll the map in the upper direction.
In the switch device, a lever tiltable in multiple directions is provided, and a plurality of switches are arranged at regular intervals around the lever. When one of the switches is pressed by tilting the lever, the switch is activated to be ON.
The plurality of switches are interconnected into a matrix form as shown in FIG. 2, so as to constitute a switch matrix circuit, and the switch matrix circuit is connected to input terminals R1-R5 of a well-known remote control IC 1.
The remote control IC 1 has two output terminals T1 and T2 through which timing signals are output to the switch matrix circuit, and has a function of converting parallel signals that are input to the data input terminals R1-R5 in response to timing signals t1 and t2, into serial signals which are then output from a transmitting terminal (not shown). The switch matrix circuit applies parallel data to the data input terminals R1-R5 of the remote control IC 1 in accordance with the switch that is activated to be ON when the timing signals t1 and t2 are received. The relationship between a pressed switch and data bits is defined, for example, as shown in Table 1.
TABLE 1 ______________________________________ State of SW t1 t2 d1 d2 d3 d4 d5 ______________________________________ Upper is ON 1 0 1 0 0 0 0 Right is ON 1 0 0 1 0 0 0 Lower is ON 1 0 0 0 1 0 0 Left is ON 1 0 0 0 0 1 0 Upper left is ON 1 0 0 0 0 0 1 Lower left is ON 0 1 0 0 1 0 0 Lower right is ON 0 1 0 0 0 1 0 Upper right is ON 0 1 0 0 0 0 1 ______________________________________
Table 1 shows that, in the case where the lever is tilted to the upper side and hence the switch positioned on the upper side is pressed, when the timing signal t1 is output from the timing signal output terminal T1, the switch matrix circuit outputs data "10000" to the input terminals R1-R5 of the remote control IC 1.
In a switch device of such a type, because the lever can be tilted in multiple directions, switches adjacent to each other may be simultaneously activated to be ON in some tilt directions of the lever.
In the conventional switch matrix circuit, the relationship between the group of switches that are activated to be ON and digital data applied to the remote control IC 1 is preset as shown in Table 1. Accordingly, for example, in the case where the switch on the upper side and the switch on the upper left side are simultaneously pressed, the switch matrix circuit outputs data "10001" when the timing signal t1 is output from the output terminal T1. As seen from Table 1, however, the data is not previously defined. As a result, the data code output through the transmitting terminal cannot be recognized and there occurs a phenomenon in which the map is not scrolled in any direction.
In the case where the switch on the upper side and the switch on the upper right side are simultaneously pressed, data "10000" is output when the timing signal t1 is output, and data "00001" is output when the timing signal t2 is output. Thus, the data code indicating that the switch on the upper side is pressed and the data code indicating that the switch on the upper right side is pressed are both output, so that it is impossible to determine which switch is pressed and hence the scroll direction is not determined.
In order to overcome the above-mentioned drawbacks, it may be contemplated that four switches are provided respectively on the upper, lower, left, and right directions of a switch lever. In such a construction, when switches on the upper and right sides are simultaneously pressed, data indicative of the upper right direction is output. However, in this construction, there exists an inevitable difference between the stroke for pressing each switch by tilting the lever in one of the upper, lower, left and right directions, and the stroke for simultaneously pressing two switches, for example, on the upper side and the upper right side by obliquely tilting the lever. This disadvantageously results in poor operability of the lever.
In the above described device, a switch element is configured by using a printed board. Such a switch element has a specific structure in which two stationary contacts are formed on the printed board by means of a print wiring technique, a rubber switch cover having an inverted-container shape is disposed on the printed board so as to cover the stationary contacts, and a movable short-circuit conductor made of, for example, electrically conductive rubber is disposed on the ceiling portion of the switch cover. In this configuration, when the switch cover is pressed by an operating unit of, for example, a push button-like shape, the movable short-circuit conductor makes contact with the two stationary contacts on the printed board to establish the electrical continuity between the stationary contacts.
When such a switch element is to be configured as a switch for simultaneously connecting one common line to, for example, two branch lines, or a 2-circuit switch as shown in FIG. 3, three stationary contacts 101a, 101b, and 101c are formed on the printed board, and a movable short-circuit conductor 102 having a size sufficient for covering the stationary contacts is disposed over the stationary contacts 101a, 101b, and 101c. A common line is connected to, for example, the stationary contact 101b, and branch lines are respectively connected to the other stationary contacts 101a and 101c.
Observation of the connecting operations of the switch circuits using the movable short-circuit conductor has shown that it is practically impossible to produce connections between the movable short-circuit conductor and the entire formation area of the stationary contacts at the exact same time. Usually, the contacting area gradually extends starting from a predetermined contact start area, depending on the structure of the operating unit or the like, to a contact terminate area. Consequently, the closing operation of the switch circuit of a stationary contact that is disposed in the vicinity of the contact start area is accomplished before that of the switch circuit of another stationary contact that is disposed in the vicinity of the contact terminate area, with the result that a time difference is produced in the closing operations of the switch circuits. In the configuration shown in FIG. 3, when the contacting area of the movable short-circuit conductor 102 gradually extends in the direction from the right side to the left side, for example, the electrical continuity between the stationary contacts 101b and 101c is first established, and the electrical continuity between the stationary contacts 101b and 101a is established with a slight time lag.
The time difference is further noticeable in the case where the operating unit is a lever supported in a tiltable manner and a movable contact is obliquely pressed in accordance with the tilting operation of the lever. Moreover, switch elements connected to a digital circuit cause data processing errors.